1. Field of the Invention
The present invention relates to high-frequency modules having a configuration in which a high-frequency switch and a high-frequency filter are mounted on a multilayer substrate, and specifically to high-frequency modules including a control signal input terminal to which a control signal for a high-frequency switch is input.
2. Description of the Related Art
In general, a front-end module is provided between an antenna and a transmitter/receiver circuit in a communication apparatus that performs communication by switching among a plurality of communication frequency bands. For example, Japanese Unexamined Patent Application Publication No. 2004-517583 discloses a front-end module including a high-frequency switch.
FIG. 1 is a circuit diagram of the front-end module illustrated in FIG. 1 of Japanese Unexamined Patent Application Publication No. 2004-517583. In this front-end module, transmission signal input portions 2 of a high-frequency switch 1 are connected to power amplifiers 13 through low pass filters 5 and 6. Reception signal output portions 3 are connected to low-noise amplifiers 14 through band pass filters 10, 11, and 12. An output portion 4 of the high-frequency switch 1 is connected to an antenna 15.
A small high-frequency module can be formed by mounting a high-frequency switch such as the one illustrated in Japanese Unexamined Patent Application Publication No. 2004-517583 on a multilayer ceramic substrate together with a diplexer and a filter. However, unless a well-designed arrangement of wiring patterns including surface electrodes of the multilayer substrate is used, there arises a problem of interference among wiring lines. In particular, in the case of a high-frequency switch that receives control data using a serial data signal and a clock signal, since the serial data signal and clock signal (high-frequency switch control signals) include many harmonic noise components, it is difficult to design the wiring for the high-frequency switch control signals.
The above problem arises not only in interference generated between the filter and the high-frequency switch but also in interference generated between the antenna and the high-frequency switch.